1. Field of the Invention
The present invention relates to a torsional damper intended for reduction of vibration and noise and which has a damping ring fixed by means of a rubber member to a hub secured to a rotating shaft such as crank shaft or the like of an internal combustion engine.
2. Description of the Prior Art
There have been proposed various types of torsional dampers, and a typical one of them is shown in FIG. 1. This torsional damper is of a structure in which a hub, not a plate, is secured to the rotating shaft. As shown in FIG. 1, a viscous fluid L is charged in the space defined between a damping ring 100 and the inner wall 102 of a hub 101. More particularly, the hub 101 is generally C-shaped in section, and thus has a circular concavity 103 in which fitted is a damping ring 100 to which a rubber member 104 and sleeve 105 are bonded by vulcanizing. The viscous fluid L is also charged in a space inside the damping ring 100.
Since the outermost circumference of the conventional torsional damper can not be used as the damping ring, namely, the damping ring is fitted in the circular concavity, the torsional damper can not have any large inertial mass. Also, since the length and sectional area of the space where the viscous fluid is charged can not be designed large, the conventional torsional damper has a small capability of damping for the required total operating space thereof.